We're 30mph through my village but because it is a 'cut through' the local government deem it to be important and the speed cannot be reduced. Even though we had two cars go round a sharp bend into a tree within a month of each other, in dry conditions.
Not Germany here but I witnessed buses of the bus company of my former city driving at 50 or more in a 30 km/h area. Some of those areas have a 30 limit because of a good reason, some probably only to add up kilometers and make the city council look good.
Speed bumps work but putting big flower pots in the way is even better. It forces people to slow down without giving them the feeling that they get slowed down for no reason.